Question

What is the relation between the direction of the force of friction and direction of motion?

Answer 1

Friction is a force that always opposes all motion; it always acts in a direction exactly opposite to that in which an object is moving (or trying to move), and typically comes when the surface rubs or drags against another as it moves.
Air resistance is a frictional force which opposes motion through air. Frictionalforces can be useful, e.g. to allow car tyres to grip the road or to slow down a falling parachutist.